Three problems related to gas recirculation valve (egr valve) have been reported for the 1997 Chevrolet Astro. The most recently reported issues are listed below.
While driving about 70 mph engine was making noise. Power steering and power brakes were affected. Technician said that problem was with idler pulley and tension pulley. After explosion like sound under the hood, the tensioner pulley disintegrated causing loss of power steering and power brakes.
Was coming to a stop light & started to apply brakes, and brake pedal went to the floor. Had no brakes. Did not hit anything. Had vehicle towed to dealer. Mechanic indicated that egr valve was opened due to carbon built up. Brake problem could be repaired, but could also reappear.
Egr valve failed.